I had something that looked like that. It was the base for a disguised low band police radio that was built to look like the stock AM radio antenna for use on an unmarked police car.. The rod part even had fake indentations to make it look like the antenna could be collapsed, like the 60's stock type car antennas. I believe the one I had was manufactured by Antenna Specialists.

Was there ham radio stuff in the mix? I do not recognize it specifically, but it appears that the bottom maybe fit over a pipe for mounting and some sort of screw was used to attach to a smaller diameter pipe. After the coax was fed thru the pipe and connected to the base. Then the donut thing seems to have three threaded holes for radials. And the top has a base to attach the vertical whip. The coil is tapped part way up and thus may have been a 5/8 wave vertical for some band probably above FM BCB, either aircraft, 2 meters, or commercial VHF. That is my best assessment of it without the actual elements being available to measure. Then again it might be for 220 MHz or even higher. But it does look kinda VHFish to me! You could presumably modify it to use as a quarter wave VHF groundplane by making it a straight shot thru to the center pin without the coil, and making quarter wave elements for the appropriate VHF range. If you need such a thing. Otherwise back in the junkbox for "someday".